TrueCharge 20 Voltage Adjustment?

[David Sanner]

I have a Xantrex TrueCharge 20 connected to two 6v US Battery for my house batteries.
(which is sometimes connected to a group 24 starting battery).

My 5 year old 6v batteries aren't what they used to be and I assumed that they
were having issues partially because I was leaving my fridge on (cold beer availability
is a must onboard) so I finally bought a 350 watt switching power supply and
a relay so that the house bank can properly charge (I've also picked up a
trickle charger for my starting battery as I don't believe that either can
properly charge when both connected to a TC20) and I can equalize the
batteries as well.

Anyway during this process I spoke with the battery manufacturer and
they told me that the TC20 wasn't putting out enough voltage during
the charging cycle (presumably during the absorption phase) and was
putting out too much during the trickle charge.

There doesn't seem to be any combination of the switch settings
(cold/warm/hot or battery type) to provide the needed range.

Has anyone opened up a TC20 or seen the schematics?
I'm hoping there might be a way to tweak the individual voltages.

Otherwise I guess when I get my next set of 6v batteries I better
make sure they'll properly charge with the TC20.

[Ron Hill]

David : That sounds like a Xantrex question to me! 

[Jon Schneider]

I spoke with the battery manufacturer and they told me that the TC20 wasn't putting out enough voltage during the charging cycle (presumably during the absorption phase) and was putting out too much during the trickle charge.

How did the battery manufacturer know?

[David Sanner]

I gave them the voltage from the front of the unit.
(and the instruction manual)

for example:  flooded/warm 14.4 & float of 13.5v

I think the batteries are 6v US2200 ... and believe the tech
guy said that they should charge near 15.5 volts and float
under 13 volts.   

I think the big problem is under volting them during
the absorption charge cycle.  I was surprised to hear
such a high voltage was required for a proper charge.

[Stu Jackson]

Dave, the TrueCharge 20 has both a temp range switch and a three stage or two stage charge and a type battery.  I'm pretty sure, but my own computer broke down and I'm working from memmory from last week's review of the manual for someone else.

Check the manual yourself.  I think the battery guys is wrong, you have deep cycle wet cells, which the TC 20 is just perfect for.

It should also charge your two banks, assuming you have separate wires from the charger to the banks.  The reserve bank doesn't need to get charged at all when you're in the slip, I'd disconnect it.

[David Sanner]

Stu, that's what I thought...   I was surprised to hear from the battery manufacturer
that their batteries liked to be topped off at such a high voltage (and floated so low).
(I have the older version of: http://www.usbattery.com/usb_us2200xc_golf.html)

Maybe we're only talking about the last few percent of charge capability or not significant
sulfation over time but they tech guy certainly didn't reassure me of that... I'd say a bit of
the opposite.

I've attached a picture from manual which is from the front of the charger
that shows the different voltages (temp/batt type).


As far as two banks on the same charger being ideal... I have my doubts as the
TC20 may have diodes on the outputs but it doesn't independently regulate the
voltage so after returning to the dock and plugging in with a reasonably
drained house bank and a fully charged starting bank I don't see how the
charger will be able to sense the proper discharge state (though maybe it
can do that independently, i doubt it) of the house bank or at least not over
charge the starting battery while charging the house bank.
(which is what happened in my case thought that might have been accelerated
due to the constant compressor load from my cold beer requirement).

Ron... my guess is Xantrex will say .7 volts doesn't matter or complain about
that model of battery... as well as mention their warranty but I'll see if
I can find the time during the day to get their official word.

It's kind of like dealing with a medical bill... who to call... the insurance
company or the doctor? ;\)

[Jon Schneider]

It's kind of like dealing with a medical bill... who to call... the insurance
company or the doctor? ;\)

Your lawyer.

[Jack Hutteball]

David, I have the same charger but with two 4D's in separate banks.  I do not have a starting battery so work off one bank only while out and alternate them to keep them up.  When I return to the dock one battery will always be down more than the other.  Each battery has a separate wire from the charger so I have always assumed that each battery would be given what it needed from the charger.  When I come back to the boat both batteries will have a "full" charge.  Looks like I could be wrong about that, but my 2 batteries at 8 years old and not as robust when new, did fine for me while out 2-1/2 weeks last summer without ever plugging in to shore power.  I am going to replace them with 4 - 6V before this cruising season gets underway.

Jack

[Stu Jackson]

As far as two banks on the same charger being ideal... I have my doubts as the
TC20 may have diodes on the outputs but it doesn't independently regulate the
voltage so after returning to the dock and plugging in with a reasonably
drained house bank and a fully charged starting bank I don't see how the
charger will be able to sense the proper discharge state (though maybe it
can do that independently, i doubt it) of the house bank or at least not over
charge the starting battery while charging the house bank.
(which is what happened in my case thought that might have been accelerated
due to the constant compressor load from my cold beer requirement).

Dave, when it gets to that point in the charging cycle, the acceptance of the batteries becomes the determining point for what the batteries will take regardless of the charger's output.  That's why I've recently been hammering acceptance to death, and now that I've got the new 2009 WM catalog, realized they'd been mentioning this all along in the advisors, albeit it subtly.

Again, the TC 20 manual isn't great in describing "how" the charger does that, just that it does do it.

[David Sanner]

Stu, good point about acceptance and if the banks are of similar size and typically
of similar discharge level (or at least alternating levels of discharge like Jack) it's
probably not an issue. However I still don't see it as ideal having a fully charged small
starting  battery get high voltage (14.5+) for several hours, time and time again, while a
large house bank goes though a lengthy absorption charge.

Maybe it's not issue if you can keep the starting battery fluid topped off but
I believe it killed my crappy 'zero maintenance' (ie. no way to refill) WM starting
battery over time (in less than 2 years).  I've replaced it with a deep cycle which
weights at least 50% more and I can add water to it!   (Again, this may have been
compounded many times over due to the cycling of the fridge)

But your point about acceptance is a good one... which basically means the
house bank should charge correctly for a typically battery if the TC20 can sense current
flow to it during the absorption phase...   and hopefully if it's not done too often
a fully charged second bank won't mind the high voltage.

I'm hoping removing the constant fridge cycling will help everything, even
if I can't get the battery manufacturer's recommended voltages from the TC20.

[Stu Jackson]

Dave, since the reserve bank is almost always FULL, that's why I keep suggesting that it NOT be charged when the house bank is "needing" a full zap.  With my combiner, it's easy to simply turn it off.  With your existing double wiring from the charger to the banks with relatively small wiring, just put a toggle switch on the reserve bank charging wire so you can turn it off.  Then you will not be in a position of "overcharging" the reserve bank.

This is exactly why I've been suggesting that folks with multiple outputs from their chargers only use one and a combiner (switched) or an echo charger, or like Jon's duo charge if you have two different battery types.

Just find a way to turn it off.

[David Sanner]

I have a poor man's combiner...  I would attach the charger wire to the
starting battery from time to time or leave the battery switch on BOTH.
However this proved less that ideal as once the battery was too
low and once, about a year ago I attached the wire and forgot about
it and my battery wound getting boiled away.

I'm hoping to take all the remembering out of it as I've
ordered a $20 1.5 amp three stage battery charger/maintainer
that I'm going to hook up to my starting battery.

I was checking out the echo charger and I'm not sure it does much
better as it still lets the voltage go up to 14.5 volts and costs
well over a $100.    Echo charger seems like a good way to
charge two banks from a single output alternator.  I just
manually combine the banks and hope I don't forget to
separate them when I turn the engine off.

Anyway I'll report back if I find out anything from Xantrex
about adjusting their voltage output.

[Stu Jackson]

Dave, that's a great idea.  Do you have a link to the product?

[David Sanner]

There are plenty of cheap deals (and perhaps questionable quality) here:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=99857

And here ...

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2724

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2909

... I'm not sure how I'll wire one in... probably by battery but I may mount
it next to where the TC20 is and just tie into the AC power and 12 lead there.

[Stu Jackson]

Dave, as a comparison to the echo charger, $12.99 is very cheap.

But I can't help but think how much less expensive a toggle switch is, probably less than $5 installed with connectors.

Your issue is that you either overcharge or neglect to charge the reserve bank.  It does not need to be charged often.  You could charge it once a month for an hour or two and be done with it.  Putting something else in that creates a constant trickle charge is just not good for the reserve bank.  Wet cells work best when fully charged and rested.  Our northern boat-out-of-water-all-winter brethren know that.   

I'm still pluggin' for the cheap toggle switch.  Put it somewhere you can see and remember to use, and your reserve bank charging issues will simply disappear.